Processor BTO options range from four cores up to the aforementioned 16; the full matrix includes "Westmere" Xeon X5670 chops running at up to 3.33GHz on the single-chip machine and 2.93GHz on the dual-processor model. Only the dual-processor model can achieve dodecacore status.
Mac Pros now offer the ATI Radeon HD 5770 graphics processor with 1GB of memory, with a BTO option of the ATI Radeon HD 5870 with 1GB of memory. Display output options include two Mini DisplayPorts and one dual-link DVI port. For storage, the 512GB SSD is now an option, and if you're feeling particularly flush you can load up with four of them.
As noted above, the machines will ship in August; the Apple Store is currently still shipping the older models.